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Mohamed Y. Hashim,Hamada M. Abdelmotalib,김종석,Dong Guk Ko,Ik-Tae Im 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6
In this present study, the particle behavior and heat transfer coefficients for particle-gas and particle-particle are found by using a computational model in a fluidization process. A conical shape is selected as a reactor due to its wide range of applications. The equations describing gas and particle motions and heat transfer are solved by using the Eulerian two-fluid approach. Glass bead particles of two different sizes (2 mm and 4 mm) are used as bed materials, and the air is used as a fluidized gas. The velocity of the gas inlet is varied from 1.3 m/s to 2.6 m/s. The results demonstrate that the particle-gas heat transfer coefficient according to the velocity of the air inlet reaches its maximum value around 2.1 m/s, then decreases thereafter. Besides, at the same velocity, the particle-particle heat transfer coefficient reaches its maximum value, then decrease thereafter with increasing the velocity of the inlet air.
Computational study of flow characteristics in a carbon fiber carbonization reactor
Abdelmotalib Hamada M.,고동국,이교우,임익태 한국탄소학회 2022 Carbon Letters Vol.32 No.5
Carbon fibers are commonly used in many specialized, high-performance applications such as race cars and aircraft due to their lightweight and high durability. The most important stage in the production of carbon fibers is the carbonization process. During this process, carbon fibers are subjected to high temperatures in the absence of oxygen to prevent fibers from burning. Labyrinth seals are attached to a carbonization furnace to prevent airflow into the furnace and to assist in the elimination of off-gases. This study investigated flow characteristics inside a carbonization furnace and the effects of different geometric parameters of labyrinth seals such as labyrinth tooth shape, number of teeth, and tooth clearance. Varying carbonization furnace operating conditions were also studied in regard to flow behavior, including fiber movement and outlet vacuum pressure. A high working gas flow rate at the furnace inlet resulted in recirculation zones. Properly regulated gas flow from the main and labyrinth inlets enabled uniform flow around the fibers’ inlet and outlet which prevented air from being trapped in the reactor. Flow behavior was minimally effected by changes to labyrinth seal geometry such as tooth length, tooth clearance, and outlet pressure. However, the movement of fibers had a clear effect on flow characteristics in the furnace.
Synergistic Activity of Paclitaxel and Sorafenib Against Liver Cancer Stem Cells
( Hend M. Nawara ),( Said M. Afify ),( Ghmkin Hassan ),( Maram H. Zahra ),( Marwa N. Atallah ),( Hager Mansour ),( Hagar A. Abu Quora ),( Amira Osman ),( Hiroki Kakuta ),( Hiroki Hamada ),( Akimasa Se 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1
Aims: Cancer stem cells (CSCs), also known as tumor-initiating cells (TICs), are suggested to be responsible for drug resistance and cancer recurrence. Current treatments with conventional chemotherapy are not highly efficient against the cancer stem cells (CSCs). The combination of anticancer drugs, of which functions are different from the other, enhances efficiency compared to the mono-therapy because it targets cancer cells in a synergistic or an additive manner. In this study, the effect of paclitaxel and sorafenib on cancer stem cells (CSCs) developed from mouse iPSCs in very low concentration was evaluated. Methods: To investigate the effect of combination therapy, CSCs were exposed to paclitaxel and/or sorafenib at different concentrations of 1, 2 and 4 nM, respectively. Cell viability was assessed with 3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazolium bromide (MTT). The same concentrations of the agents were assessed for the effect on the self-renewal potential of CSCs subpopulation by sphere formation ability. Results: As a result, a combination of sorafenib and paclitaxel significantly reduced the resistance while the CSCs exhibited drug resistance against paclitaxel alone. Also, combination of these agents reduces the self-renewal potential of CSCs when compared to single treatment. Simultaneously, combination significantly suppressed not only the colony formation but also the tube formation of the Cancer stem cells. Conclusions: These results suggest the combination therapy of paclitaxel and sorafenib in low doses be an attractive approach to target cancer stem cells in the future.
Entesar A. Hassan,Hamada M. Mashaly,Zeinab M. Hashem,Salem E. Zayed,Ahmed M. Abo-Bakr 한국섬유공학회 2022 Fibers and polymers Vol.23 No.9
A series of varying and poly-functionalized heterocyclic compounds 3a-c, 4d-k, 6a,b, 8, 9, and 12 containing azofunction have been synthesized using 2-(1-(4-aminophenyl)ethylidene)malononitrile (1) and/or its diazonium salt as buildingblocks. In addition, new pyridazine derivatives 4a-c, 7a,b, and 13a-f were synthesized. Subsequent treating of the resultedazo dyes moieties with different reagents in conventional and green conditions using microwave irradiation and shrimp chitinas a green catalyst; homo- and hetero-molecules containing azo dyes were gathered. The obtained azo dyes were applied onfabrics at high temperatures and their properties such as washing fastness using standard soap (SDS) and rubbing fastness(wet and dry) under controlled conditions of pressure, speed, and moisture were studied. In addition, they were screened fortheir biological activities on two bacterial and two mycolic species. The synthesized products were characterized by theirelemental and spectral analyses such as IR, MS, 1H-NMR, and 13C-NMR spectra. The produced dyestuffs 3a-c, 4d, f, h, i, j,6a,b, 8, and 12 were dyed on polyester fabrics, and subsequently their dyeing properties and their light, washing, perspiration,rubbing, and sublimation fastness was determined and the dyed samples showed very good fastness levels to rubbing,washing, thermal fixation, good light, and possessed very good perspiration fastness.
A Bioactive Fraction from Streptomyces sp. Enhances Maize Tolerance against Drought Stress
Warrad Mona,Hassan Yasser M.,Mohamed Mahmoud S.M,Hagagy Nashwa,Al-Maghrabi Omar A,Selim Samy,Saleh Ahmed M.,AbdElgawad Hamada 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.8
Drought stress is threatening the growth and productivity of many economical crops. Therefore, it is necessary to establish innovative and efficient approaches for improving crop growth and productivity. Here we investigated the potentials of the cell-free extract of Actinobacteria (Ac) isolated from a semi-arid habitat (Al-Jouf region, Saudi Arabia) to recover the reduction in maize growth and improve the physiological stress tolerance induced by drought. Three Ac isolates were screened for production of secondary metabolites, antioxidant and antimicrobial activities. The isolate Ac3 revealed the highest levels of flavonoids, antioxidant and antimicrobial activities in addition to having abilities to produce siderophores and phytohormones. Based on seed germination experiment, the selected bioactive fraction of Ac3 cell-free extract (F2.7, containing mainly isoquercetin), increased the growth and photosynthesis rate under drought stress. Moreover, F2.7 application significantly alleviated drought stress-induced increases in H2O2, lipid peroxidation (MDA) and protein oxidation (protein carbonyls). It also increased total antioxidant power and molecular antioxidant levels (total ascorbate, glutathione and tocopherols). F2.7 improved the primary metabolism of stressed maize plants; for example, it increased in several individuals of soluble carbohydrates, organic acids, amino acids, and fatty acids. Interestingly, to reduce stress impact, F2.7 accumulated some compatible solutes including total soluble sugars, sucrose and proline. Hence, this comprehensive assessment recommends the potentials of actinobacterial cell-free extract as an alternative ecofriendly approach to improve crop growth and quality under water deficit conditions.
S.Hamada,Y.Ohino,N.Nishi,M.Nakaoka 전력전자학회 1989 ICPE(ISPE)논문집 Vol.- No.-
This paper describes a new constant frequency phase-shifted mode PWM DC-DC power converter, which incorporates two-stage inverters with high-frequency transformer links and saturable reactors as non-linear elements. The proposed converter performs an efficient zero-voltage switching under a large load range (no limitation for load range) and a wide voltage regulation range. Its steady-state characteristics are evaluated and discussed through computer-aided simulation and experimental results. The feasible experiments were carried out with a 0.5kW-500kHz breadbord and power conversion efficiency more than 88% was obtained.<br/>
Hamano, Y.,Hamada, Y.,Miyahara, M.,Kobayashi, S.,Terashima, Y. Asian Australasian Association of Animal Productio 1998 Animal Bioscience Vol.11 No.4
The present study was conducted to examine the effects of dietary protein (20, 22, 24%) with a constant protein-to-energy ratio on clenbuterol-induced performance in broilers. The protein-to-energy ratio was based on adequate level (22% protein, 3,100 kcal of energy). Female broiler chickens were used for a $3{\times}2$ factorial arrangement and fed diets with or without 1 ppm clenbuterol from 14- to 32-days of age. Feed efficiency improved with increasing dietary protein level, regardless of clenbuterol treatment. The dietary clenbuterol increased weights of breast and leg muscles (gastrocnemius and peroneus longus), and clenbuterol markedly reduced protein content of leg muscles in chickens fed the 20% protein diet, but did not in chickens fed the 22 and 24% protein diets. Feeding the 24% protein diet with clenbuterol improved the protien accretion (peroneus longus) by 8.4%. Clenbuterol decreased DNA content and increased the protein/DNA ratio in breast muscle regardless of dietary protein intake. Clenbuterol had no effect on RNA content in both breast and leg muscles. The present results demonstrated that various protein levels which retain the same protein-to-energy ratio in the diet markedly alter the protein accretion induced by ${\beta}$-agonist in broilers.